When is the last frost in St. Louis, MO?

The average last spring frost (50% probability of 32°F) in St. Louis is around April 1, based on NOAA/NCEI 1991–2020 normals at the St Louis Sci Ctr, MO station (4.2 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in St. Louis?

The average first fall frost in St. Louis, MO is around November 4, giving roughly a 218-day frost-free growing season.

What planting zone is St. Louis, MO?

St. Louis is in USDA plant hardiness zone 7a (average annual extreme minimum temperature 0 to 5°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in St. Louis?

In St. Louis, MO the warmest month is July (avg high 88.5°F) and the coldest is January (avg low 22°F). It averages about 42.8″ of precipitation a year and 13.8″ of snow.

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St. Louis, MO Planting Calendar & Frost Dates

USDA hardiness zone 7a · ZIP 63101 · elevation 122′ · NOAA & USDA data

St. Louis is in USDA hardiness zone 7a (winters can dip to 0 to 5°F), with a growing season of about 218 days between the average last spring frost (April 1) and first fall frost (November 4). The warmest month is July (avg high 88.5°F); the coldest is January (avg low 22°F). It averages 42.8″ of precipitation a year and 13.8″ of snow, mostly mid-winter. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp 0 to 5°F

Last spring frost

April 1

avg (50% prob, 32°F)

First fall frost

November 4

avg (50% prob, 32°F)

Growing season

218 days

frost-free window

Warmest month

July

avg high 88.5°F

Month-by-month typical weather in St. Louis

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Cahokia, IL (4.5 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	40.7	22	31.4	2.7	4.9
February	46	25.6	35.8	2.3	3.7
March	56.1	34.7	45.4	3.6	1.2
April	67.5	45.4	56.5	4.6	0.3
May	76.1	56	66	4.8	0
June	84.8	64.9	74.8	4.3	0
July	88.5	68.9	78.7	5	0
August	87.3	66.7	77	3.1	0
September	80.3	58.6	69.5	3.4	0
October	69.5	46	57.7	3	0
November	56.2	35.3	45.7	3.3	0.8
December	45.1	26.6	35.8	2.8	2.9

What to plant when in St. Louis

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: February 18 · Transplant out: April 8
Peppers	warm	Start seeds indoors: February 4 · Transplant out: April 15
Cucumbers	warm	Direct sow: April 8
Zucchini / squash	warm	Direct sow: April 8
Bush beans	warm	Direct sow: April 8
Sweet corn	warm	Direct sow: April 8
Basil	warm	Transplant out: April 8
Peas	cool	Sow (spring): February 25 · Sow (fall): September 9
Spinach	cool	Sow (spring): February 18 · Sow (fall): September 9
Lettuce	cool	Sow (spring): March 4 · Sow (fall): September 9
Kale	cool	Transplant (spring): March 11 · Sow (fall): August 26
Broccoli	cool	Transplant (spring): March 18
Carrots	cool	Sow (spring): March 11 · Sow (fall): August 26
Onions	cool	Transplant (spring): March 4
Potatoes	cool	Plant seed potatoes: March 18
Radishes	cool	Sow (spring): March 4 · Sow (fall): September 23

Dates are computed from St. Louis's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Missouri

Florissant, MO St. Charles, MO Chesterfield, MO St. Peters, MO Cape Girardeau, MO Jefferson City, MO Columbia, MO Springfield, MO

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — St Louis Sci Ctr, MO, 4.2 mi (confidence: high). Monthly weather normals: Cahokia, IL, 4.5 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.